I have been reading a lot on the forums, and what I first thought would just be an easy board swap from a donar HD to my failed HD, now seems non feasible. The board on my 7500 is burnt, it actually produced smoke when connected. I was hoping to just replace the board from another drive, but from what I have been reading on here, it sounds quite difficult.
Does the guide on here for a 5000 pertain to 7500?

PCB swaps means adaptive swaps too on this one. Search on TVS and go from there this one might help you out. I know there are 1000+ post here lately on TVS and you will get the info from them to test your TVS and move forward. If it is only your board and you did not damage to your Preamp inside the HSA then you might be fine in changing it. But if you have problems in the preamp in your HSA then you need professional help on this one. Search first and try it and if you do not get it working seek professional help in changing out the HSA on this drive.

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Iorana Haraharaini

Where did the smoke come from?

Does your board have an 8-pin chip at location U12?

Could we see a detailed photo?

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A backup a day keeps DR away.